[RFC PATCH v2 1/2] PM / domains: Introduce multi PM domains helpers

[Daniel Baluta <daniel.baluta@oss.nxp.com>]

From: Daniel Baluta <daniel.baluta@nxp.com>

This patch introduces helpers support for multi PM domains.

API consists of:

1) dev_multi_pm_attach - powers up all PM domains associated with a given
device. Because we can attach one PM domain per device, we create
virtual devices (children of initial device) and associate PM domains
one per virtual device.

2) dev_multi_pm_detach - detaches all virtual devices from PM domains
attached with.

Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
---
 drivers/base/power/common.c | 93 +++++++++++++++++++++++++++++++++++++
 include/linux/pm_domain.h   | 19 ++++++++
 2 files changed, 112 insertions(+)

diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
index bbddb267c2e6..6d1f142833b1 100644
--- a/drivers/base/power/common.c
+++ b/drivers/base/power/common.c
@@ -228,3 +228,96 @@ void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
 	device_pm_check_callbacks(dev);
 }
 EXPORT_SYMBOL_GPL(dev_pm_domain_set);
+
+/**
+ * dev_multi_pm_attach - power up device associated power domains
+ * @dev: The device used to lookup the PM domains
+ *
+ * Parse device's OF node to find all PM domains specifiers. For each power
+ * domain found, create a virtual device and associate it with the
+ * current power domain.
+ *
+ * This function should typically be invoked by a driver during the
+ * probe phase, in the case its device requires power management through
+ * multiple PM domains.
+ *
+ * Returns a pointer to @dev_multi_pm_domain_data if successfully attached PM
+ * domains, NULL when the device doesn't need a PM domain or when single
+ * power-domains exists for it, else an ERR_PTR() in case of
+ * failures.
+ */
+struct dev_multi_pm_domain_data *dev_multi_pm_attach(struct device *dev)
+{
+	struct dev_multi_pm_domain_data *mpd, *retp;
+	int num_domains;
+	int i;
+
+	num_domains = of_count_phandle_with_args(dev->of_node, "power-domains",
+						 "#power-domain-cells");
+	if (num_domains < 2)
+		return NULL;
+
+	mpd = devm_kzalloc(dev, GFP_KERNEL, sizeof(*mpd));
+	if (!mpd)
+		return ERR_PTR(-ENOMEM);
+
+	mpd->dev = dev;
+	mpd->num_domains = num_domains;
+
+	mpd->virt_devs = devm_kmalloc_array(dev, mpd->num_domains,
+					    sizeof(*mpd->virt_devs),
+					    GFP_KERNEL);
+	if (!mpd->virt_devs)
+		return ERR_PTR(-ENOMEM);
+
+	mpd->links = devm_kmalloc_array(dev, mpd->num_domains,
+					sizeof(*mpd->links), GFP_KERNEL);
+	if (!mpd->links)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < mpd->num_domains; i++) {
+		mpd->virt_devs[i] = dev_pm_domain_attach_by_id(dev, i);
+		if (IS_ERR(mpd->virt_devs[i])) {
+			retp = (struct dev_multi_pm_domain_data *)
+				mpd->virt_devs[i];
+			goto exit_unroll_pm;
+		}
+		mpd->links[i] = device_link_add(dev, mpd->virt_devs[i],
+						DL_FLAG_STATELESS |
+						DL_FLAG_PM_RUNTIME |
+						DL_FLAG_RPM_ACTIVE);
+		if (!mpd->links[i]) {
+			retp = ERR_PTR(-ENOMEM);
+			dev_pm_domain_detach(mpd->virt_devs[i], false);
+			goto exit_unroll_pm;
+		}
+	}
+	return mpd;
+
+exit_unroll_pm:
+	while (--i >= 0) {
+		device_link_del(mpd->links[i]);
+		dev_pm_domain_detach(mpd->virt_devs[i], false);
+	}
+
+	return retp;
+}
+EXPORT_SYMBOL(dev_multi_pm_attach);
+
+/**
+ * dev_multi_pm_detach - Detach a device from its PM domains.
+ * Each multi power domain is attached to a virtual children device
+ *
+ * @mpd: multi power domains data, contains the association between
+ * virtul device and PM domain
+ */
+void dev_multi_pm_detach(struct dev_multi_pm_domain_data *mpd)
+{
+	int i;
+
+	for (i = 0; i < mpd->num_domains; i++) {
+		device_link_del(mpd->links[i]);
+		dev_pm_domain_detach(mpd->virt_devs[i], false);
+	}
+}
+EXPORT_SYMBOL(dev_multi_pm_detach);
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 9ec78ee53652..5bcb35150af2 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -183,6 +183,13 @@ struct generic_pm_domain_data {
 	void *data;
 };
 
+struct dev_multi_pm_domain_data {
+	struct device *dev; /* parent device */
+	struct device **virt_devs; /* virtual children links */
+	struct device_link **links; /*  links parent <-> virtual children */
+	int num_domains;
+};
+
 #ifdef CONFIG_PM_GENERIC_DOMAINS
 static inline struct generic_pm_domain_data *to_gpd_data(struct pm_domain_data *pdd)
 {
@@ -369,18 +376,27 @@ struct generic_pm_domain *of_genpd_remove_last(struct device_node *np)
 
 #ifdef CONFIG_PM
 int dev_pm_domain_attach(struct device *dev, bool power_on);
+struct dev_multi_pm_domain_data *dev_multi_pm_attach(struct device *dev);
 struct device *dev_pm_domain_attach_by_id(struct device *dev,
 					  unsigned int index);
 struct device *dev_pm_domain_attach_by_name(struct device *dev,
 					    const char *name);
 void dev_pm_domain_detach(struct device *dev, bool power_off);
 int dev_pm_domain_start(struct device *dev);
+void dev_multi_pm_detach(struct dev_multi_pm_domain_data *mpd);
 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd);
+
 #else
 static inline int dev_pm_domain_attach(struct device *dev, bool power_on)
 {
 	return 0;
 }
+
+struct dev_multi_pm_domain_data *dev_multi_pm_attach(struct device *dev)
+{
+	return NULL;
+}
+
 static inline struct device *dev_pm_domain_attach_by_id(struct device *dev,
 							unsigned int index)
 {
@@ -396,6 +412,9 @@ static inline int dev_pm_domain_start(struct device *dev)
 {
 	return 0;
 }
+
+void dev_multi_pm_detach(struct dev_multi_pm_domain_data *mpd) {}
+
 static inline void dev_pm_domain_set(struct device *dev,
 				     struct dev_pm_domain *pd) {}
 #endif
-- 
2.17.1